Book Image

Bash Quick Start Guide

By : Tom Ryder
Book Image

Bash Quick Start Guide

By: Tom Ryder

Overview of this book

Bash and shell script programming is central to using Linux, but it has many peculiar properties that are hard to understand and unfamiliar to many programmers, with a lot of misleading and even risky information online. Bash Quick Start Guide tackles these problems head on, and shows you the best practices of shell script programming. This book teaches effective shell script programming with Bash, and is ideal for people who may have used its command line but never really learned it in depth. This book will show you how even simple programming constructs in the shell can speed up and automate any kind of daily command-line work. For people who need to use the command line regularly in their daily work, this book provides practical advice for using the command-line shell beyond merely typing or copy-pasting commands into the shell. Readers will learn techniques suitable for automating processes and controlling processes, on both servers and workstations, whether for single command lines or long and complex scripts. The book even includes information on configuring your own shell environment to suit your workflow, and provides a running start for interpreting Bash scripts written by others.
Table of Contents (10 chapters)

Cleaning up after a script

Dropping temporary files without cleaning them up is a little untidy; at the end of a script where temporary files are used, we should have a safe rm command to remove them afterward:


# Code setting and using tempdir goes here, and then ...
# Remove the directory
if [[ -n $tempdir ]] ; then rm -- "$tempdir"/myscript-timestamp rmdir -- "$tempdir" fi

Notice that we're careful to check that tempdir actually has a value, using the -n test before we run this code, even if we don't think anything might have changed it; otherwise we'd be running rm -- /myscript-timestamp.

Notice also that we're carefully removing only the files we know we've created, rather than just specifying "$tempdir"/*. An empty value for the tempdir variable in such a case could have terrible consequences!

The preceding...